Circuit interrupting device



(No Model.) 3 Sheets-Sheet 1.

A. WURTS. CIRCUIT INTERRUPTING DEVIGE.

No. 470,773. Patented Mar. 15, 1892.

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(No Model.) a Sheets-Sheet 2.

A. WURTS.

- GIRGUIT INTERRUPTING DBVIGE.

No. 470,773. Patented Mar. 15,1892.

Zihzcsses 7 MW dziwlgyinfor UNITED STATES PATENT OFFIcE.

ALEXANDER XVURTS, CF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO THE\VESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, OF SAME PLACE.

ClRCUlT-iNTERRUPTiNG DEVICE.

SPECIFICATION forming part of Letters Patent No. 470,773, dated March15, 1892.

Application filed December 1, 1891. $erial No. 413,749. (No'modeh) Toall whom it may concern.-

Be it known that I, ALEXANDER WURTs. a citizen of the United States,residing in Pittsburg, in the county of Allegheny and State ofPennsylvania, have invented a new and useful Improvement inCircuit-Interrupting Devices, (Case No. 472,) of which the following isa specification.

The invention relates to certain improvements in the construction andorganization of apparatus fori nterrupting electric-circuit connectionsand for preventing the maintenance of electric arcs where it isdesirable that these should be extinguished-as, for instance, inlightning-arresters, electric fuses, man ual and automatic switches,(to.

i }It is frequently desirable in operating electric apparatus that thecurrent be allowed to momentarily traverse a given circuit and that thiscircuit or the flow of current therethrough should be then automaticallyinterrupted. \Vhen the flow of currents of high electro-motive force isthus interrupted, it is very difficult to prevent the formation of adestructive electric arc, and various different forms of arc-rupturin gdevices have therefore been employed for protecting such circuits. Ithas been customary to protect electric circuits from injury by lightningby providing an interrupted circuit to the earth, the break in thecontinuity of the circuit being formed by slightly-separated confrontingplates. The currents which normally traverse the circuit are not ofsuificient potential to strike an arc across the air-gap between theplates; but in the event of lightning striking the circuit or inducingin it a charge differing in potential from that of the earth the inducedelectro-motive force becomes sufficient to strike an arc across theair-space, and thus allow the lightning or induced charge to escape tothe earth. The generated current usually employed for electric lightingand electric railways is liable by reason of its high electro-motiveforce to continue to flow across such an air-gap and maintain the arewhen it has been thus established, and injury may result to thegenerating apparatus by reason of the comparatively low resistance ofthe short circuit thus formed. For this reason various devices have beenemployed for automatically extinguishing the are immediately after thelightning discharge has taken place. In other instances closed circuitsare allowed under certain conditions to receive an abnormalcurrent,which current then opens some portion of the circuit, and means have tobe provided for extinguishing the are which tends to form at the pointof interruption. For example, in the case of an electric fuse employedfor antomatically interrupting a circuit when it is traversed by anabnormal current it is desirable that some means be provided forpreventing an are from being maintained between the melted ends of thefuse. Again, it is frequently desirable to employ a switch forinterrupting the connections of a circuit normally carrying currents ofhigh electro-motive force, and in such case special means should beprovided for preventing a destructive arc from being formed ormaintained between the electrodes of the switch.

My invention is applicable to these several uses, and in general it isuseful wherever it is desirable to prevent the formation or continuanceof a destructive electric are.

It should be stated that the invention is particularly useful inconnection with alternatin g electric current-s of high electro-motiveforce; but it is also useful with currents continuous in direction.

My invention consists in employing as electrodes between which themaintenance of an arc is to be prevented blocks or electrodes of certainmetal or metals, as hereinafter particularly set forth, and presentingproper surfaces to each other and acting to introduce such resistance inthe intervening air-gap as to prevent the continuance of the flow ofcurrent. These electrodes are arranged and connected in circuit indifferent manners, according to the purpose for which employed.

I have found that if two cylinders of zinc placed side by side andseparated by a very narrow space are made to form the terminals of anelectric circuit, and if an electric are be started between the two, thearc will antomatically extinguish itself. Other forms of electrodes thancylindrical will also serve the purpose; but usually I have found itdesir- ISO ways. maybe placed side by side and the central able to havethe electrodes present narrow lines of confronting surfaces, and it alsoseems desirable to have such an amount or surface area of metal as willprevent the body of metal from becoming heated to an intense degree. Ihave found, also, that compounds of zincsuch, for instance, as brass-maybe used instead of zinc and other compounds of zinc, and also pureantimony and various compounds of antimony.

The precise manner in which this device operates to extinguish the arcis not clearly ascertained; but it is probable that a slight amount ofthe zinc or antimony is volatilized by the current, producing an oxideof the metal inthe form of a vapor, and such a vapor is a non-conductorof electricity, and this non-conducting vapor then becomes a barrier tothe passage of the current, and thus interrupts its flow. This theory,however, is not advanced as being necessarily the correct theory, butone which affords a probable explanation of the operation.

The specification will set forth clearly the manner of constructing theapparatus, whatever be the true explanation of its mode of operation. I

I make use of the invention in various For instance, three of theseelectrodes one connected with the earth, while thetwo outer on-es'areconnected with the respective sides of an electric circuit. Lightningdis charges may then take place across the intervening air-gaps to theearth; but the moment the line has been relieved of the hightensioncurrent caused by the lightning the arcs between the two outerelectrodes and the central one, which might otherwise tend to'cause ashort circuit of the machine, are automatically interrupted.

In order to use this device with an electric fuse, the electrodes,separated from each other in the manner set forth, may be connected in ashunt-circuit around the terminals of the fuse. When the fuse is meltedby the passage of an abnormal current,there is usually a tendency forthe current from the generator to continue the are once establishedbetween the melted onds of the fuse, the vapors of the metal or alloyforming the fuse serving as a conductor. The circuit-interrupter inshunt upon the fuse offers a path for the current, and an arc willmomentarily form across the space between its electrodes, thuswithdrawing the current from the melted ends of the fuse, and this arewill then automatically extinguish itself. The invention may besimilarly applied to switches, both manual and automatic, and in fact toany electric ap paratus where it is desirable to permit an are tomomentarily exist between two electrodes.

I have found that two electrodes such as have been described whenseparated one thirty-second of an inch and connected directly to theterminals of a one-thousand-volt alternator will not maintain an areunder any Different numbers of electrodes may be er'nployed in differentinstances to suit the circumstances and electrodes of other form thancylindrical-for instance, hexagonal, beveled, spherical, &c.may beemployed.

In the accompanying drawings I have illustrated several diiferent formsand applications of the circuit-interrupter.

,In the-drawings, Figure 1 is a diagram showing the invention applied toa lightningarrester, the electrodes being cylindrical in form. Fig.2 isa plan of the lightning-arrester. Fig. 3 is a similar view showing asemi-cylindrical form of electrodes. Fig. 4: illustratessphericalelectrodes. Fig. 5 illustrates parabolic surfaces. Fig. 6illustrates parabolic surfacesin combination with spherical electrodes.Fig. 7 illustrates hollow cylindrical electrodes. Fig. 8 illustrateshexagonal form of electrodes. Fig. 9 is an elevation of a fuse equippedwith the arc-arresting device. Figs. 10 and 11 are respectively an endview and plan of the fuse attachment. Figs. 12 and 13 illustrate anapplication of the invention to a switch.

Referring to Figs. 1 and 2, A represents a generator of electricity, andL L main-line conductors leading therefrom. The main line is shown ashaving its terminals connected with a work-circuit-for instance, theprimary coil 19 of an alternating-current converter 0. The secondarycoils of this converter supplies translating devices d. Short cylindersE E of hard brass or zinc or antimony or compounds thereofsuch as brass,&c.are connected with the respective conductors L L and an interposedcylinder E of similar material is connected with the earth at G. It isevident that if an are be established be- IIO tween the electrodes E Eand likewise beprovided the mass of metal is suflicient toprevent theelectrodes becoming melted, yet it may be desirable to give dataregarding some of the forms which I have found in practice to operatesuccessfully. I have used cylinders of brass of about one and a quarterinches in length and one inch in diameter separated by a space varyingfrom one sixtyfourth to one-sixteenth of an inch, likewise brass rodsone-half inch long and one-half inch in diameter, and have obtained veryexcellent resultssuch, for instance, as interrupting circuits ofone-thousand-volt alternating-current generators. It should also benoticed that with an alternating current better results seem to beobtained by placing the electrodes in very close proximity, and it wouldseem that ordinarily the distance which they should be separated shouldbe but slightlyin excess of that required to prevent the normal currentupon the circuit to which the apparatus is applied from jumping acrossthe air-gaps.

I11 Fig. 3 I have indicated semi-cylindrical electrodes in place of thecylindrical ones shown in Figs. 1 and 2. Such form operates verysatisfactorily and gives nearly, if not quite, as good results as thecylindrical form.

Spherical blocks-such as shown in Fig. 4 may also be employed with goodresults and also parabolic surfaces, as shown in Fig. 5. In thisinstance the central electrode E is shown as constructed with both endshaving parabolic surfaces, while the blocks 6 e have only the ends whichconfront the electrode 6 constructed with parabolic surfaces.

In Fig. 6 the electrodes E E are spherical, while the central electrodeE is similar in shape to that shown in Fig. 5.

In Fig. 7 the same general structure as shown in Figs. 1 and 2 isemployed, with the exception that the electrodes are hollow instead ofsolid.

In Fig. 8 hexagonal forms are employed, angles of the electrodes beingpresented to each other. It will also be understood that any suitablematerial coated with the metal may be used.

111 Figs. 9, 10, and 11 the device is illustrated as employed inconnection with an electric fuse F, which may be of any suitableform--as, for instance, a safety strip or fuse of lead or alloy whichwill melt at any desired temperature. This fuse is in shunt upon theelectrodes E E and its ends are secured in slots E formed in theelectrodes, or they may be coupled thereto in any other convenientmanner. The entire device is shown as connected in a conductor L,leading from the generator A, and if a current of abnormal strengthtraverses this conductor it will melt the fuse F. Such an interruptionof the circuit is liable to create a tendency for an arc to be formedacross the air-space between the electrodes, and the formation of suchan arc will withdraw the are from the melted ends of the fuse. The arebetween the electrodes is then itself immediately interrupted by theautomatic action of the arc-rupturing device.

In Figs. 12 and 13 the invention is illustrated in connection with acircuit closing and opening switch S. hen such a switch is opened, thereis a tendency for an arc to form at the separating switch-plates. Suchan arc may be drawn away from the switch-plates by the are-rupturingdevice, as in the case of the fuse; but it may be desirable in someinstances to have the electrodes E E rest in contact with each otherwhile the switch is closed and to provide means for separating themimmediately after the switch is opened. This may be done in differentwaysas, for instance, by means of a iioirconducting wedge K upon theswitch-lever, one of the electrodes E being movable with reference tothe other E It may be observed that the number of electrodes employed inconnection with the fuse and the switch may be varied, as it is notnecessary that there should always be three. There may be two or four ora greater num ber, according to the circumstances.

IVhile I have spoken particularly of zinc and antimony and theircompounds, it may be added that bismuth, cadmium, mercury, and amalgamsalso appear to possess the qualities of extinguishing the arc, and itmay be possible that other substances may be found which will have therequired characteristics; but it may be added that I have tried copper,carbon, aluminium, steel, iron, and various other substances withoutobtaining the same satisfactory results as from the metals and compoundsabove mentioned.

I claim as my invention- 1. An arc-rupturing device consisting of two ormore electrodes of zinc, antimony, or compounds thereof or othermaterials having a non-conducting vaporous oxide, substantially asdescribed.

2. An arc-rupturing device consisting of blocks of brass or itssubstantial equivalent of large radiating surface relative to theirconfronting surfaces, substantially as described.

3. The combination of two or more electrodes containing zinc or antimonyor equivalent metal placed adjacent to each other and having confrontingdiverging surfaces, said electrodes having a large radiating surfacerelative to their confronting surfaces, snbstantially as described.

4. A device for preventing the maintenance of an electric arc,consisting of electrodes adjacent to each other, composed of masses ofmetal having curved confronting surfaces, and an electric fuse havingits terminals in electrical connection with the respective masses ofmetal.

5. A lightning-arrester for electric circuits, consisting of electrodesof brass or its equivalent of large mass and diverging surfaces,substantially as described.

6. A lightning-arrester for electric circuits, consisting of parallelbars of brass or equivalent material placed in close proximity to eachother and having their confronting surfaces diverging, substantially asdescribed.

7. The combination, with an electric circuit, of two electrodesconstituting terminals of the circuit and composed of a metal whoseoxide is a non-conductor of electricity.

8. The combination, with an electric circuit, of two electrodesconstituting terminals are, which consists in generating by means of theare a non-conducting vapor Within the path of the are and by such vaporincreasing the resistance offered to the passage of the current untilthe arc is extinguished, substantially as described.

In testimony whereof I have hereunto subscribed my name this 23d day ofNovember, A. D. 1891.

ALEXANDER WURTS.

Witnesses: v

R. D. MERSHON, J. W. SMITH.

